1. Dynamic Resource Transaction for Femtocell BSs Document Number: C80216m-0810 Date Submitted: 2009-04-24 Source: Hung-Yu Wei, Yih-Shen Chen, I-Kang Fu, Shih-Lung Chao Email: hywei@cc.ee.ntu.edu.twhywei@cc.ee.ntu.edu.tw NTU/MediaTek yihshen.chen@mediatek.comyihshen.chen@mediatek.com Venue: IEEE Session #61, Cairo, Egypt Base Contribution: This is base contribution Re: IEEE 802.16m-09/0021, “Call for Comments on Project 802.16m System Description Document (SDD)” - CR to SDD: Chapter 15 Support of Femtocell Purpose: For TGm members’ discussion and approval Notice: This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. 2 Frequent Handover due to Small Coverage Frequent handover will happen to the Mobile Stations (MS) when deploying many small-coverage femtocells into the network –The coverage of femtocell is much smaller (e.g. 35m) than the coverage of macro cells (e.g. 5000m) This will result in huge signaling and traffic overhead in backhaul network. But MS will still suffer service disruption due to radio link switching. However, it takes time to route user’s traffic to femtocell BS but MS will leave the femtocell in a short time (e.g. 1 sec).

3. 3 Low Resource Utilization due to Interference Avoidance Higher frequency reuse factor will result in lower system capacity –Ensure the worst case SINR can meet min. QoS requirement For coverage guarantee (e.g. Example I) –Lower resource utilization results in lower capacity Worst case scenario only happens occasionally, but the permanent resource reservation for frequency reuse is expensed.

4. 4 Radio Resource Management in Macrocell/femtocell Overlay Self-organizing network configuration would improve the spectral utilization efficiency Flexible radio resource management scheme needed to serve –Heterogeneous users –Various application traffic –Time-varying interference condition

5. 5 Overview: Dynamic Resource Transaction Self-organizing RRM enhances resource utilization efficiency –Overlay Macro-Femto network architecture –Adaptive radio resource allocation between basestations Macro-to-femto Femto-to-macro Femto-to-femto Observations –Traffic burstness for data applications –Traffic load variation in femtocells (especially CSG femto)

6. 6 Dynamic Resource Transaction (1/3) Proposed resolution to resolve the aforementioned problems: –High speed MS will not handover into the cell with small coverage For high speed MS, macrocell BS will not grant MS’s handover request to femtocell –Negotiate a predefined radio resource region shared by each cell for normal case –Macrocell BS will schedule high speed MS be served by that negotiated resource region Under the negotiation result though the proposed resource transaction mechanism in following slides –Femtocell BS will reschedule its subordinated MSs not be served by that negotiated resource region when the high speed MS served by macrocell BS is approaching its coverage

7. 7 Dynamic Resource Transaction (2/3) Proposed methods for detecting a MS served by macrocell BS is approaching the femtocell : –For Uplink, femtocell BS monitors the SINR of its subordinated MSs which are scheduled be served by that negotiated resource region. If the measured SINR is suddenly dropped, the femtocell BS can expect another MS served by macrocell BS is approaching –For Downlink, macrocell BS monitors the SINR reported by its subordinated MSs which are scheduled be served by that negotiated resource region. If the reported SINR is suddenly dropped but there is no much change on radio link parameters, the macrocell BS can expect that MS is approaching femtocell coverage

8. 8 Dynamic Resource Transaction (3/3) –LBS information: AMS reports its positioning information, and then macrocell BS informs the femtocell BS on its moving path. These femtocell BSs will reserve the pre-defined resource region for the possibly approaching MS –LBS+snooping: AMS reports its positioning information, and then macrocell BS informs the femtocell BS on its moving path. These femtocell BSs will Start to monitor the uplink signal quality of the pre-defined resource region Those region is allocated with lower priority upon the monitoring If the signal quality is lower than a threshold, those region may be forbidden to use

9. 9 Scenario1: Dynamic Radio Resource Transactions in Macrocell/femtocell Overlay

10. 10 Request to Release Radio Resource due to Interference Macrocell may asks an overlaid femto BS to temporarily or permanently release certain radio resource usage (e.g. some frequency channel or subcarriers) when –For example, upon receiving interference report from other base station –For example, based on its interference measurement results that meet certain interference condition criteria Similarly, femto BS may request its neighboring BS to release certain radio resource usage

11. 11 Request to Release Radio Resource Due to Interference: Exemplary Signaling Flow macroBSfemtoBS 2 Interference report (f2) Acknowledge Resource Release Request (release f2) femtoBS 1 Use: f1, f2, f5 Use: f1, f5 Stop using channel f2

12. 12 Some Exemplary Dynamic Radio Resource Transactions Macrocell/femtocell overlay architecture –Adaptive resource allocation between overlay macro/femto or between adjacent femtocells –Handle radio resource “transactions” between BSs Resource Request –Ask for more resource (e.g. from overlay macro BS) Resource Grant –Grant for resource request (e.g. Macro BS grant the request of overlaid femto BS) Resource Release –Release unused resource permanently Resource Rent –Release unused resource temporarily Resource Status Reporting –Exchange resource and interference information Resource Negotiation (bargaining) –Negotiate resource between peers (femto-to-femto) –It handle resource “transactions” between BS-BS – BS-to-MS RRM might be conducted integratedly or independently The above radio resource transactions between BSs might be applied to neighboring femto BSs

13. 13 Scenario 2: Dynamic Radio Resource Transactions between Femtocells femtoBS may release or temporarily rent radio resource (time slots or frequency carriers) to neighboring cells – the resource transaction might be 1 BS to 1 BS 1 BS to multiple BSs

14. 14 Dynamic Resource Exchange for Interference Mitigation This design is similar to the “Request to Release Radio Resource Due to Interference” design –Resource Exchange : the BS might create strong interference (in certain resource block: e.g. subcarriers, or frequency bands) to others –MacroBS asks the interfering BS to release certain radio resource usage. Meanwhile, macroBS offers some other radio resource to the interfering BS for exchange. Similarly, a femto BS might offer its neighboring BS for dynamic Resource Exchange (ask to stop using some resource and give some extra resource)

15. 15 Dynamic Resource Exchange for Interference Mitigation: Exemplary Signaling Flow macroBSfemtoBS 2 Interference report (f2) Acknowledge Resource Release Request (stop f2, give f4) femtoBS 1 Use: f1, f2, f5 Use: f1, f4, f5 Stop using channel f2 Start using channel f4

16. 16 Interference Mitigation Between Neighboring Femtocells femtoBS 2 Interference Mitigation Alert (f2) femtoBS 1 Adjust Tx power in channel f2 When femtoBS1 detect excessive interference caused by femtoBS2, femtoBS1 could send an Interference Mitigation Alert to femtoBS2 femtoBS 2 may adjust its transmission power accordingly femtoBS 2 may initiate dynamic resource transaction (e.g. exchange resource to reduce interference)

17. 17 Text Proposal [Adopt the following text modification into section 15.8 of the P802.16m SDD]

18. 18 Text Proposal [Adopt the following text modification into section 16.2 of the P802.16m SDD]